Locking vertices to rotate the object around them
When you use forward kinematics, moving the body will move the arm and hand to follow the body motion. 

When you use inverse kinematics (IK) the hand can be positioned and will stay stationary while moving the body. Note that a hand using IK will normally pull away from the location if the length of the arm doesn't reach the location desired.

By animating only clive's body you can see that the hand using IK stays still while the hand using FK moves with the body.



If you enable the rigify addon, you can add a meta rig and generate the final rig to get an armature that has IK/FK controls that you can look at. There are also many rigging tutorials that cover IK controls.